Preserving Food through Drying
There are many different ways to preserve food so that it doesn’t spoil and can be used later.
We will talk about the different ways to store food over the next few weeks, where they are especially effective, where they don’t work so well, and tips and tricks to use.
This post will focus on Drying or Dehydrating as an easy means to preserve food.
The most common way is through the use of a dehydrator, but drying can also be done in the sun and even the oven.
Sun drying is recommended primarily for fruits. Since drying food outdoors takes a longer time, the high sugar and acid content of fruits are needed to keep food from spoiling while drying. Meats or vegetables are not recommended for sun drying as they may spoil before they dry completely.
Sun drying takes several days with a minimum temperature is 85° required. Hot, breezy days are best when dehydrating outdoors. Ideally, humidity should be less than 60%. So, if you live in an area that is primarily rainy or humid, sun drying isn’t a good choice.
When sun drying, the food is set in direct sunlight on a tray or rack. Since it takes several days, the food must be covered or brought inside overnight so that the cool air doesn’t condense moisture onto the food and reverse the drying process.
You will also need to find a way to protect the food from birds, who would find your fresh fruit quite appealing.
Some people use ovens to dehydrate their food, but this can be tricky because many ovens will not sustain a temperature setting high enough to safely dehydrate and low enough to dry the food rather than cook it.
If you want to use an oven, you must control the temperature manually by turning the oven on and off and opening and closing the door. You will need an oven thermometer that registers the low temperatures needed for dehydrating.
Types of Dehydrators
There are many types of dehydrators available. Each dehydrator has a heating element, some sort of fan, and trays. Most have some sort of temperature control, either digital or a knob/dial.
Fans & Heating Elements
Some of the least expensive units have the heating element and fan on the bottom where the trays stack on top of one another. The problem with these units is that the bottom trays dehydrate quickly while those on the top take much longer. To combat this issue, you must rotate the trays during the process so that everything dries evenly.
Other units have the element and fan at the back of a cabinet-like enclosure. These work more like a low temperature convection oven. They are much better at providing even dehydration, but there are still differences that may affect performance.
Some dehydrators have the vent on the top. In this configuration, the air is circulated around and through the trays, and exits through the top of the cabinet. This ensures that the trays on the top get sufficient airflow.
This type of unit should not be placed under cabinets or in any enclosed space that blocks the top. You should not leave anything sitting on the top of the unit.
Other dehydrators have vents on the sides. In these units, the air circulates around the trays and exits through slits in the side of the cabinet. This is fairly effective, but I have found that the trays at the top and bottom don’t dry as well.
If you have this type of unit, you may need to rotate the trays from top/bottom to the middle. If you don’t use all of the trays, fill the middle area of the unit first. These units can be put under a cabinet, but need clearance on the sides.
No matter what type of dehydrator you use, you need to monitor the process and adjust as needed. Some have doors you can see through while others require you to take off a lid or open a solid door.
These are all considerations when choosing the unit that best meets your needs.
Each dehydrator comes with either plastic or metal trays. Some have lips that help keep food on the tray while others are almost completely flat. In either case, the trays are a mesh with rather large holes. In order to dehydrate smaller items, either a fine mesh or non-stick sheet must be used on the tray.
Another factor when considering which dehydrator to get is the noise.
I have 2 dehydrators.
One is smaller (only 9 trays), dries food fairly quickly, and is relatively quiet (about 60 decibels – the volume of normal conversation at 3 ft.).
The other is much larger (12 huge trays), takes a little longer to dry because of the vent configuration and seems much louder. It actually isn’t really any louder (I measured it), but it seems like it because it has a bit of an occasional rattle when the element kicks on.
Neither of these should be put close to where someone is sleeping. They should also be kept away from moist environments such as laundry rooms.
I actually use my dehydrators outside when drying strong or pungent foods (onions, garlic, etc.). I also don’t dehydrate mushrooms in the house because I don’t want to spread the spores in the air.
Just as in all methods of food preservation, you should pick the best quality food to dehydrate. The dehydration process will not improve rotting or spoiled food.
Fruits and vegetables should be thoroughly washed and prepared prior to dehydrating.
Most foods are sliced, diced, or sectioned prior to drying. Some foods require additional processing such as blanching first to stop the action of enzymes that could change the flavor, texture or color of food.
An example of this is potatoes. Without blanching, potatoes will turn black during the dehydrating process and will look very unappealing. They are still fine to eat, but most people have an aversion to eating black foods.
Blanching can also break down the cell walls allowing the food to dehydrate faster as well as improving texture upon rehydration. This is especially true with broccoli (which maintains its bright green color if blanched), grapes (blanching helps crack the skin to allow drying), and cranberries (they will take FOREVER to dry if not blanched to crack the skin).
When slicing or dicing food, remember that thin, uniform pieces dehydrate faster and more uniformly than thick or variably sized bits.
There are standard temperatures for different types of food. This chart gives you a guideline to follow when choosing a setting on a dehydrator.
|Type of Food||Temperature|
|Meats, Poultry, Fish||155°F/68°C|
The higher the moisture level of the food, the longer it will take to dehydrate. Trays that are more tightly packed will also take more time to dehydrate. I like to dehydrate as much as I can at once, so I have dehydrators that can perform well even with packed trays.
Dried fruits and meats can be eaten as is when they are dried and make great snacks, think raisins, fruit leather and jerky.
Dried vegetables, however, are better for use in soups and stews. They are hard to chew when they are dry and they do not rehydrate to the exact same form as when they
Most meat jerky is made from thinly sliced lean cuts of meat that have been marinated for several days in a seasoned sauce.
This is a great video that shows you all the ins and outs of making great jerky.
You may not have the vacuum sealed marinating tank, but there are other options available to the home jerky maker, such as the FoodSaver marinating container.
The dehydration process causes foods to shrink in size and many times changes the shape of the food. Once rehydrated, the food may not have quite the same shape as the original.
This is a picture of a diced piece of yellow bell pepper that has been rehydrated. Note the slightly deformed shape. It was a straight sided dice when it was fresh.
This was after a very short rehydration period. It may regain more of its original shape as it is cooked.
Most dehydrated vegetables can be put in stews, soups, casseroles, and other dishes while still dry, provided there is enough water to properly rehydrate them.
They can also be used in pasta salads and boiled with the pasta to rehydrate. They generally do not rehydrate well to be eaten raw, such as in a salad.
Dehydrated fruits are much better eaten in their dried form. They do not hold up to the rehydration process very well.
Dehydrate Almost Anything
You can dehydrate almost anything. Some foods can be dehydrated to make powders (blueberries, kale, tomato paste, onions) while others are dehydrated for snacks (grapes, apples, bananas, marshmallows). Still others are just used to provide nutritious vegetables in food when they aren’t in season.
Think of the foods and recipes you use. What can be replaced with a dehydrated version? Many foods that are bought pre-processed and packaged in the store are actually dehydrated foods.
Dehydration makes the food take up a lot less space while weighing only a fraction of its original form. Dried foods maintain nutrients, especially if dehydrated at lower temperatures.
How Can You Tell if It’s Done?
Foods need to cool in the dehydrator for about an hour before you check to see if they are dry. If you check them without cooling first, they may still feel soft because they are warm.
If they are warm, and you don’t think they’re dry enough, you may put them in for more time which may make them overdone. Instead, let foods cool, then check for dryness.
Different foods have different characteristics when they are dry. Foods that are full of sugars may always be a little pliable and sticky (think bananas and pineapple chunks). This doesn’t mean that the food isn’t done.
Especially for fruits, overdrying causes foods to get very hard. If you overdry something, it may not be suitable for anything but powdering.
Don’t leave your food in the dehydrator for long after it has cooled. Otherwise, it will start pulling the moisture out of the air and rehydrating.
There is nothing more frustrating than forgetting trays in the dehydrator and having to restart the machine because the food has started to become soft again.
After removing your food from the trays, transfer it into a glass mason jar if possible. If a glass jar isn’t available, a Ziploc bag will do for short-term storage.
You’ll want to have an airtight seal as any air that gets in the jar may have moisture that can start rehydrating your food. This moisture can cause spoilage.
An easy way to check for moisture in your sealed jar, is to put it in the refrigerator and watch for condensation on the inside of the jar. In the winter, I like to put mine on the back porch for a little while.
Keep the dehydrated food sealed in the jar for a few days, occasionally shaking it to make sure the contents are dry and loose. Any sticking together (other than high sugar items) may be caused by moisture and would require putting the food back in the dehydrator for a few more hours.
Drying food is a very forgiving process. If the food isn’t dry enough, just rotate the trays and put it back in. If only a small portion isn’t dry, pull off the dried food and continue dehydrating the rest.
Once your dried food is conditioned, it’s time to store it for long-term.
Dehydrated foods that you’ll be using regularly in your cooking can be kept in mason jars on a shelf in your pantry. They should be vacuum sealed if possible using the jar attachment for a FoodSaver. Your jars should also be stored in a dark, cool place.
For longer-term storage, I recommend sealing dehydrated foods in Mylar bags with oxygen absorbers added.
I use 7-mil quart and gallon size bags I got from my local IFA Store. They have the best price I’ve found anywhere. They are Harvest Right bags sold for storing home freeze-dried foods. The most common Mylar bags available online are 5-mils thick and should be sufficient for most uses.
Mylar bags offer protection from air and light, both of which can degrade your product. They do not, however, protect against rodents. Your Mylar bags should be stored in a plastic tote or bucket to add a layer of protection.
Look for my upcoming posts on how to dehydrate some specific foods. In case you missed it, here’s my post on making Blueberry powder.
What foods would you like to learn how to dehydrate? Let us know in the comments below and we’ll try to make it happen.